The present invention relates to a variable displacement swash plate compressor.
Japanese Laid-Open Patent Publication No. 1-219364 describes an example of a variable displacement swash plate compressor. The compressor includes a cylinder housing, which includes a cylinder chamber, a shaft, which is rotatably supported in the cylinder housing, a swash plate, which rotates integrally with the shaft, and a piston, which reciprocates in the cylinder chamber. First and second compression chambers are arranged at the opposite ends of the piston. The first and second compression chambers draw in fluid, compresses the fluid, and discharges the compressed fluid. The compressor also includes a support member arranged coaxially with the shaft. The support member pivotally supports the swash plate. The support member moves the central portion of the swash plate along the axis of the shaft and changes the inclination of the swash plate. In the first compression chamber, the corresponding piston is movable to positions where the piston draws in, compresses, and discharges fluid regardless of the inclination of the swash plate. The second compression chamber includes a dead space the volume of which changes in accordance with the inclination of the swash plate. The compressor further includes first, second, and third suction passages. The first suction passage guides fluid into a second suction chamber that is in communication with each second compression chamber. The second suction passage guides fluid into a first suction chamber that is in communication with each first compression chamber. The third suction passage allows the fluid to be sent to the second suction chamber bypassing the first suction passage.
The first and second suction passages of the compressor disclosed in the publication allows the fluid to first flow toward the second suction chamber. Thus, the fluid circulates over a large area in the compressor and effectively cools and lubricates each portion of the compressor. In addition, the third suction passage allows the fluid to be sent to the first suction chamber bypassing the first suction passage. This ensures that a large amount of fluid is sent to the first and second suction chambers when the compressor operates under a maximum displacement condition.
However, in the compressor of the publication, the drawn in fluid would have to pass through the swash plate chamber and a shaft sealing device before reaching the first and second chambers. The swash plate chamber accommodates sliding parts such as the swash plate, and the shaft sealing device also includes a sliding part. These sliding parts act as heat sources that heat the suction fluid. The heated drawn in fluid reduces the compression efficiency. In particular, the sliding parts including the swash plate generate more heat during a large displacement operation. This increases the temperature of the drawn in fluid and adversely affects the compression efficiency.